Mass murder (in military contexts, sometimes interchangeable with "mass destruction") is the act of murdering a large number of people (four or more), typically at the same time or over a relatively short period of time. According to the FBI, mass murder is defined as four or more murders occurring during a particular event with no cooling-off period between the murders. A mass murder typically occurs in a single location in which a number of victims are killed by an individual or more. Most acts of mass murder end with the death of the perpetrator(s), whether by direct suicide, suicide by cop or being killed by law enforcement.

Mass murder may be committed by individuals or organizations. Mass murder may also be defined as the intentional and indiscriminate murder of a large number of people by government agents. Examples are the shooting of unarmed protestors, the carpet bombing of cities, the lobbing of grenades into prison cells and the random execution of civilians. Mass murderers are different than spree killers, who kill at two or more locations with almost no time break between murders and are not defined by the number of victims, and serial killers, who may kill large numbers of people over long periods of time. The largest mass killings in history have been attempts to exterminate entire groups or communities of people, often on the basis of ethnicity or religion. Some of these mass murders have been found to be genocides and others to be crimes against humanity, but often such crimes have led to few or no convictions of any type.

Anders Behring Breivik (Norwegian pronunciation: ['andəʂ 'beːɾiŋ 'bɾæɪʋiːk]; born 13 February 1979) is a Norwegian accused mass murderer, terrorist and the confessed perpetrator of the 2011 attacks in Norway. On 22 July 2011, Breivik bombed the government buildings in Oslo, which resulted in eight deaths. He then carried out a mass shooting at a camp of the Workers' Youth League (AUF) of the Labour Party on the island of Utøya where he killed 69 people, mostly teenagers.

Two pairs of court-appointed psychiatrists have examined Breivik prior to his 2012 trial. In the first report Breivik was diagnosed with paranoid schizophrenia. A second evaluation was commissioned following widespread criticism of the first report. One week before the start of his trial the second psychiatric evaluation was published with the conclusion that Breivik was not psychotic during the attacks and he was not psychotic during their evaluation; rather he is an extreme narcissist. The trial of Anders Behring Breivik began on 16 April 2012 and is scheduled to last 10 weeks. The main issue to be decided in the trial is whether he can be given a prison sentence or, if the court finds him legally insane, he will be involuntarily sectioned to a psychiatric facility, possibly indefinitely. Contrary to popular belief, Norway's forensic psychiatric process means a psychiatric diagnosis could for Breivik mean more - rather than less - time in prison, even if he were successfully treated.

Howard Barton Unruh (January 21, 1921 – October 19, 2009) was an American mass murderer (sometimes classified as a spree killer) who killed 13 people on September 6, 1949, in Camden, New Jersey, when he was 28 years old. Unruh is considered the first single-episode mass murderer in U.S. history. He died in 2009 after a lengthy illness at the age of 88. The incident became known as the "Walk of Death".

Unruh was the son of Samuel Shipley Unruh and Freda E. Vollmer. He had a younger brother, James; he and Unruh were raised by their mother after the parents separated. He grew up in East Camden, attended Cramer Junior High School, and graduated from Woodrow Wilson High School in January 1939. The Woodrow Wilson High School yearbook from 1939 indicated that he was shy and that his ambition was to become a government employee.

Always a reserved man, he had turned into a recluse in the three months before his spree. The World War II veteran was unemployed and lived with his mother. During the war, he was reportedly a brave tank soldier who served in the Battle of the Bulge and kept meticulous notes of every German killed, down to details of the corpse. He was honorably discharged in 1945, and returned home with a collection of medals and firearms. He decorated his bedroom with military items, and set up a target range in his basement. His mother supported him by working at a factory while Howard hung around the house and attended daily church services. He briefly attended a pharmacy course at Temple University in Philadelphia but dropped out after only three months.

Edward John "Eddie" Izzard (born 7 February 1962) is an English stand-up comedian, actor, and writer. His comedy style takes the form of rambling, whimsical monologue and self-referential pantomime. He had a starring role in the television series The Riches as Wayne Malloy and has appeared in many motion pictures such as Ocean's Twelve, Ocean's Thirteen, Mystery Men, Shadow of the Vampire, The Cat's Meow, Across the Universe, The Chronicles of Narnia: Prince Caspian and Valkyrie. He is also the voice of Nigel in the 2006 animated film The Wild and Miles Axlerod in the 2011 Disney/Pixar animated film Cars 2.

He has cited his main comedy role model as Monty Python, and John Cleese once referred to him as the "Lost Python". In 2009, he completed 43 marathons in 51 days for Sport Relief in spite of having no prior history of long distance running. He is also known for his transvestism. He has won numerous awards including a Primetime Emmy Award for Individual Performance in a Variety or Music Program for his comedy special Dress to Kill, in 2000. Izzard's web site won the Yahoo People's Choice Award and earned the Webby Award.

Buju Banton (born Mark Anthony Myrie 15 July 1973) is a Jamaican dancehall, ragga, and reggae musician. Banton has recorded pop and dance songs, as well as songs dealing with sociopolitical topics.

He released early dancehall singles in 1991, but came to prominence in 1992 with two albums, including Mr. Mention, which became the best-selling album in Jamaican history upon its release. Banton signed with major label Mercury Records and released Voice of Jamaica the following year. By the mid-1990s, Banton had converted to the Rastafari faith, and his music undertook a more spiritual tone. His 2010 album Before the Dawn was the winner for Best Reggae Album at the 53rd annual Grammy Awards.

Banton gained international notoriety early on in his career for the anti-gay track "Boom Bye Bye", as well as for his 2009 arrest and conviction on drug conspiracy and firearms charges, for which he is currently serving a ten-year federal prison sentence in Federal Transfer Center with a scheduled release date of January 2019.